Soil particulate organic matter

It is important to localize organic matter in soil matrix and study the soil organic matter which undergoes decomposition. In this study, soil structure was investigated by the use of X-ray computed tomography, a non-destructive technique which allows studying the undisturbed 3D soil pore network structure. The research was aimed to find an appropriate staining agent that stains the OM but not the mineral particles. This would help to enhance the contrast between the pore space and the OM. The artificial mineral matter- OM mixtures were prepared for contrast enhancement staining. These included mixtures of fine sand+ coarse silt, fine sand+ fine silt and fine sand+ coarse silt+ particulate organic matter. Then, four different staining agents that have OM staining ability were used viz., Phosphomolybdic acid (PMA), Silver nitrate, Lead acetate trihydrate and Lead nitrate. Among, the four staining agents used, PMA and Lead nitrate were regarded very promising staining agents to stain POM in soils containing coarse silt. The study showed that there was higher C mineralization when organic substrates were added into soil.